Leptospirosis can be spread by urine splash to 

 the face of other animals, but spreading via water 

 is the more common and normal situation in epi- 

 demics. A piped water supply may not affect the 

 distribution of such diseases as anthrax, blackleg, 

 botulism, bacillary hemoglobinuria, and footrot 

 infections, all of which occur in circumstances in- 

 volving various water-related environmental fac- 

 tors. For example, soil and rainfall distribution 

 materially influence the occurrence of these dis- 

 eases. Preventive management practices should in- 

 clude a sanitary water system which does not pond 

 or puddle water on the yards or pastures. Such dis- 

 eases as dysentery, typhoid, and cholera of man 

 also have their counterparts in livestock produc- 

 tion. A pathogen-contaminated water supply 

 should no more be permitted for livestock than 

 for the human because the separation of human 

 and animal pathogens in their ability to cause 

 disease is not distinct. 



The economic importance of optimum water 

 intakes by farm animals is obvious. Thus, palata- 

 bility and toxicity due to dissolve mineral salts 

 are of concern. The most abundant mineral salts 

 present in surface and deep-well waters are the 

 carbonates, bicarbonates, chlorides, and sulfates 

 of sodium, potassium, magnesium, and calcium. 

 Together they comprise 95 to 99 percent of the 

 total mineral content of most natural waters. 

 Water begins to decrease in palatability when the 

 total amount of these minerals exceeds from 500 

 to 1,000 mg/1, depending on the nature and com- 

 bination of the minerals. Beyond these limits, the 

 water becomes increasingly unpalatable and fi- 

 nally toxic. The common belief that cattle and 

 sheep are more tolerant to highly mineralized 

 waters than poultry, swine, and horses may not 

 be true. Limited research work indicates little 

 species differences in salinity tolerance when the 

 moisture content of the rations is similar. 



Practical experience and a limited amount of 

 controlled experimental work indicate that chick- 

 ens, swine, cattle, and sheep can survive and re- 

 main healthy on saline waters containing up to 

 15,000 mg/1 of minerals such as bicarbonates, 

 chlorides, and sulfates of sodium and calcium and 

 up to 10,000 mg/1 for the corresponding salts of 

 potassium and magnesium. The limits of tolerance 

 to alkaline waters, those containing sodium and 

 calcium carbonates, are around 5,000 mg/1. 



Surface and underground waters nearly always 

 contain trace amounts of toxic minerals. Of these, 

 lead, arsenic, selenium, chromium (hexavalent 

 forms), cadmium, silver, barium, and fluorine are 

 cumulative poisons. When present in excess, they 

 are not eliminated from the body fast enough to 



prevent the buildup of toxic levels in the bones, 

 soft tissue, and other body parts. They thus be- 

 come hazards .to man who consumes them as well 

 as to the animal which may very well survive the 

 insult and reach market without outward notice- 

 able effect. Many other minerals, such as salts of 

 zinc, copper, manganese, and iron, are also pres- 

 ent. However, they are not cumulative poisons and 

 become toxic at much higher levels. 



A quantitative mineral analysis of water is 

 highly informative relative to its content of lead, 

 arsenic, and other toxic minerals. In only a few 

 cases will these minerals be present in harmful 

 amounts. In nearly all cases, the decisive factor 

 affecting the suitability of water will be the amount 

 of sodium, potassium, magnesium, and calcium 

 contained. 



Since no two waters are similar in their relative 

 content of sodium, potassium, magnesium, and cal- 

 cium, no attempts have been made to determine 

 the exact magnitude of their detrimental effects 

 on water and feed intakes and feed efficiencies 

 during the time required to develop tolerance to 

 them. The detrimental effects will be roughly pro- 

 portional to the total amount of these four minerals 

 in excess of 1 ,000 mg/1. 



Variable considerations 



Geographical 



The foregoing discussion has implied some- 

 thing of the breadth and diversity of the -water 

 pollution situation as it bears on domestic live- 

 stock. Some classification of the resultant prob- 

 lems is possible on the basis of the variety of fac- 

 tors influencing pollution. 



Certain geographical areas of the United States 

 are recognized as related to specific types of water 

 contamination. These may be concerned with geo- 

 logical soil formation, or with production patterns 

 indigenous to the areas in question. Examples 

 of the first type are the presence of boron in natural 

 waters of Southern California and of sulfates as 

 teachings from gypsum and other soil minerals in 

 several of the Western States. An indirect exam- 

 ple of the same relationship is the effect that cer- 

 tain alkaline soil conditions have upon the pH of 

 soil water and the subsequent implications for 

 viability of livestock disease organisms. Micro- 

 organisms responsible for erysipelas in swine, 

 sheep, and turkeys, vibrio fetus in cattle and 

 sheep, and vibrio dysentery ("winter dysentery") 

 of cattle all thrive in an alkaline medium (13). 



462-246 O - 72 - 10 



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